I'm thinking of speedrunning an old game, but I only have it on PS Now

PS Now is not an emulation service. PS Now is a streaming service. From what I understand, the actual game is being ran by actual hardware in one of Sony's many properties. Then, the output is just streamed to you, while your inputs are sent to them. So it should be good to go, although you will experience input lag at the very least that someone that had the console itself wouldn't experience. So you're really just disadvantaging yourself.

Okay, thank you.

I'm running a game that only two other people have run.

Your best bet in all situations is to go to the game's forum and ask there. Just because PS Now isn't an emulator doesn't mean that it's accepted for the game. I can't imagine there being any issues, but...

There is only one moderator, and he's inactive.

Worst comes to worse, I'll just buy a PS3